Data code conversion for remote signalling and control systems

ABSTRACT

A MESSAGE IS FORMED BY THE OUTPUT PULSES SUCCESSIVELY DELIVERED BY A CHAIN OF (M+1) MONOSTABLE MULTIVIBRATORS, THE FIRST ONE DELIVERING A SYNCHRONIZING PULSE OF DURATION 3T, THE OTHER M ONES (THE TIME CONSTANT OF WHICH IS MADE EQUAL TO T OR 3T/2 ACCORDING TO THE BINARY SIGNAL TO BE TRANSMITTED) DELIVERING THE INFORMATION PULSES. WHEN A MESSAGE HAS BEEN TRANSMITTED A FEED BACK LOOP TRIGGERS THE TRANSMISSION OF A FURTHER MESSAGE. THE DECODER COMPRISES A SYNCHRONIZING PULSE DETECTOR AND A CHAIN OF M BISTABLE MULTIVIBRATORS CONTROLLED BY THE RECEIVED SIGNALS TO RESTITUTE THE PULSE GENERATED IN THE CODER BY THE FIRST M MONOSTABLE MULTIVIBRATORS, AND M CIRCUITS FOR DETECTING THE DURATION OF THESE PULSES.   D R A W I N G

Feb. 13, 1973 R. JACQUET 316;836

DATA CODE CONVERSION FOR REMOTE SIGNALLING AND CONTROL SYSTEMS Filed May14, 1971 3 Sheets-Sheet 1 R. JACQUET Feb. 13, 1973 DATA CODE CONVERSIONFOR REMOTE SIGNALLING AND CONTROL SYSTEMS Filed May 14, 1971 3Sheets-Sheet 2 ME SDZ mj miw E E N N N i a a A, F o L? Q a. F o .n F o fo E: O 1 d: E, E3 Em E3 E0 :5 E0 E0 :3 E0 :3 NEIL $2 DE 22 25 22 a2 E252 E2 E2 J l x 5 E 3 O 3 m g fi 5 r I B I A M52556 II 25 Om 55kg ta :5zpwmta 55:5 A 7 w E E Q Q 5 L 5 22 um/5%; x322 qezz 232: 5% 8 g E I l l1 l A E 913% r mfil M M1 W f WTJ E55 5 a 3 5 2 Feb. 13, 1973 JACQUET3,716,836

DATA CODE CONVERSION FOR REMOTE SIGNALLING AND CONTROL SYSTEMS Filed May14, 1971 3 Sheets-Sheet 5 J M mu n L 10L L 9 10, 1 2 5 4 Im 1 E l I'Ll''l fLl 'i L O I i f 15 I I I L+.

Q 5 I L. P1 1 i 1 r I I l I Q2 I P2 I 4 "Jm I Qm I IIIII 7* Pm I v 50 l".m 51 I I United States Patent US. Cl. 340167 R 5 Claims ABSTRACT OFTHE DISCLOSURE A message is formed by the output pulses successivelydelivered by a chain of (m+1) monostable multivibrators, the first onedelivering a synchronizing pulse of duration 3T, the other m ones (thetime constant of which is made equal to T or 3T/2 according to thebinary signal to be transmitted) delivering the information pulses. Whena message has been transmitted a feed back loop triggers thetransmission of a further message.

The decoder comprises a synchronizing pulse detector and a chain of mbistable multivibrators controlled by the received signals to restitutethe pulses generated in the coder by the first m monostablemultivibrators, and m circuits for detecting the duration of thesepulses.

The present invention relates to improvements in data coders anddecoders, and more particularly to the coders and decoders of remotecontrol and remote signalling transmissions systems.

In the time-division multiplex technique which is conventionally used,the generally large number of signals which have to be transmittedrequires a precisely defined timing of the operations of coding anddecoding, the time required by each signal being assigned at thetransmitting end by a timing unit which is under the control of a clock,a similar clock being provided at the receiving end.

The coded signal comprises a synchronization pulse and m further pulses,each of which, according to the duration thereof, conveys an information1 or O, i.e. the presence or absence of a predetermined fact or order.

If the number m originally used happens to be no longer adequate, thetiming unit and other parts of the transmitter coder and of the receiverdecoder have to be modified.

It is an object of the present invention to simplify the coder circuitsat the transmitting end and the decoder circuits at the receiving end ofthe data-transmission system, by discarding the clocks and theassociated circuits. Through making it possible to use modular designs,that is to say ones based upon elementary functional units, theinvention achieves wide flexibility in assembly, enabling readyadaptation to the number m of effective signals to be achieved and thusavoiding the ditliculties encountered in the known designs.

In accordance with the present invention, there is provided: a datacoder, having an output, for the coding of messages comprising asynchronizing signal and a number m of successive binary informationpulse signals, each of which has a duration T or T according to thevalue 0 or 1 of the corresponding binary information, said coderincluding, for the generation of said m binary signals, a circuitcomprising: in monostable multivibrators connected in series andrespectively associated with said m binary signals, said multivibratorshaving respective inputs and outputs; means for adjusting the timeconstant of each one of said m multivibrators to one or the other of thevalues T +T, or T +T,, where T, is a fixed duration, according towhether the corresponding binary sigice nal is to have the duration T orT triggering means for triggering the first one of said m multivibratorsinto its semistable state, and a circuit coupled to said mmultivibrators for deriving from the pulse signals generated by said mmultivibrators corresponding shortened pulses, the duration of which isdecreased by said duration T and directing said shortened signals,separated by intervals of duration T toward said output.

In accordance with the invention, there is further provided a datadecoder adapted for decoding the messages coded by means of a coder asclaimed in claim 1, said decoder comprising: an input for receiving saidcoded data; first means coupled to said input for detecting saidsynchronizing signal; m bistable multivibrators respectively associatedwith said m binary signals and connected in series so that each one ofthe first (m-l) bistable multivibrators when passing from its secondstate into its :first state causes the following one to be triggeredinto its second state; coupling means between said first means and thefirst one of said m bistable multivibrators for triggering said firstbistable multivibrator into its eec- 0nd state; further means controlledby the trailing edges of the respective received binary informationpulse signals for respectively triggering back the associatedmultivibrators into their first states; and m output circuits,respectively coupled to said m bistable multivibrators, for deliveringone or the other of two predetermined signals according to whether theduration of the pulse signal delivered by the associated multivibratoris T d-T, or T1+T1- Other characteristics will be apparent from theensuing description given purely by way of non limitative example andillustrated in the drawings where:

FIG. 1 is a block diagram of one embodiment of the coder of a remotecontrol data transmitter in accordance With the invention;

FIG. 2 is a block diagram of one embodiment of a corresponding decoder;

FIG. 3 is a time diagram illustrating the operation of the coder anddecoder of FIGS. 1 and 2.

The invention will be described by way of example, assuming that thecoder and decoder are those of a remote control transmission system.

The coder of FIG. 1 comprises n=m--'2 identical monostablemultivibrators M to M having a common DC. voltage source V, and the timeconstant of which, i.e. the duration of the semistable state of which inresponse to a single triggering pulse, is T. This duration may beextended for each multivibrator M (i=3, 4 m) to 3T/2, through insertingan additional resistor r, between the voltage source and the feedingpoint of the multivibrator. The corresponding switching is effected bymeans of an electronic switch B connected in parallel with the resistorr, and which, when closed, acts as a bypass for this resistor. The nmultivibrators are respectively associated with 71 data to be conveyed,the closing and opening of the switch B, respectively corresponding tothe values 0 and 1 of the ith datum, and the control inputs C of the nswitches being the inputs of the coder.

The output of each switch B, is on the other hand connected to aterminal of a connection strap 5,, the other terminal of which isconnected to one or the other of two OR-circuits, 1 and 2, according towhether the value i of the ith information should be considered as anurgency case or as a routine one.

The coder comprises three further multivibrators 3, M and M The timeconstant of the multivibrator 3 is equal to 3T. The multivibrators M andM are provided with time constant control systems of the same type asthose of the multivibrators M to M the corresponding resistanceinsertion systems not being shown but for the auxiliary inputs 4 and 5,playing for the multivibrators M and M the same part as the inputs C,for the multivibrators M to M The monostable multivibrators 3 and M, toM are serially connected, the output used for the multivibrator 3delivers an inverted signal, i.e. the resting voltage, which will heassumed to be zero, when the multivibrator 3 is in its semistable stateand a voltage 1 when the multivibrator is in its stable state. Theoutputs used for multivibrators M; to M. deliver a noninverted signal,i.e. a pulse of amplitude 1 when they are in their semistable states.The signal inputs of the (In-+1) multivi brators are such that eachmultivibrator is triggered into its semistable state for a decreasinginput signal, i.e. the trailing edge of a positive signal.

The outputs of the OR-circuits 1 and 2. are respectively connected tothe time constant control inputs 4 and 5 of the multivibrators M and MThe outputs of the multivibrators 3, and M to M, are respectivelyconnected to the (m-l-l) inputs of an (JR-circuit 9 through respectivedifierentiators D and D to D the first of which D comprises an. outputpolarity inverter.

The output of the OR-circuit 9 is connected to the input of a furthermonostable multivibrator 10, the duration of the semistable state ofwhich is T/2. The output used for this multivibrator delivers the aforedescribed inverted signal. Its input is such that the multivibrator istriggered into its sernistable state for negative input pulses. Theoutput of the multivibrator 10 is connected on the one hand to thesignal input of the multivibrator 3 and on the other hand to the inputof an amplifier 11, the output of which is the output of the coder.

The operation of the coder will be described with the help of FIG. 3,the upper portion of which shows as function of time the signalsdelivered by the multivibrators 3, M to M. and 10.

Through the inputs C each switch B, is made nonconductive when the ithdatum has the value 1, the corresponding multivibrator being then saidto be in its condition 1.

If at least one of those 1 informations is an urgent case, theOR-circuit 1 applies to the time constant control input 4 of themultivibrator M, a voltage setting it to its condition 1.

In the same way, if there is at least an information 1 which is anordinary one (i.e. not urgent), the OR-circuit 2 sets the multivihratorM to its condition ill-3! It is thus seen that the multivibrators M andM in this example are used to convey information items which are derivedfrom the 11 original data, the corresponding signals being used at thereceiving end to actuate two signalling systems, the first of whichindicating that a message has been received with at least one urgentinformation 1, and the second one indicating that a message has beenreceived with at least one non-urgent information 1.

Apart from the fact that the two considered information items areservice ones, they are coded, transmitted and decoded exactly in thesame manner as the others so that no difference need be made in thefollowing between the cases of the multivibrator M and M and M to M andtheir respective associated circuits.

The information items stored in the multivibrators M to M aretransmitted in the following way:

Assuming that at time 0 the multivibrator 3 receives a triggering pulse,maintaining it in its semistable state, and the multivibrator 10 returnsto its stable state while all the other multivibrators are in theirstable states, the operation is as follows:

The multivibrator 3 returns to its stable state at time 3T. Theditferentiator D thus delivers a short negative pulse which, through theOR-circuit 9, triggers the multivibrator 10 into its semistable state;this in turn brings back the multivibrator 3 to its semistable state,the

'4 latter having thus delivered at its output a very short positivepulse (FIG. 3), the duration of which is disregarded in the descriptionof the timing of the system.

The trailing edge of this pulse causes the multivibrator M to pass intoits semistable state for a duration 3T/2 or T according to whether ithas been previously set to condition 1 or 0 (the first case has beenassumed in FIG. 3).

At time 3T-l-T/2, the multivibrator 10 returns to its stable condition,having thus delivered, since time t:(), a positive pulse 1,, of duration3T, followed by a zero level of duration T/2, this pulse 1,, being thesyn chrcnization pulse of the message to be transmitted.

At time 3T+T or 3T+3T/2 (the latter being the case assumed in FIG. 3)the multivibrator M returns to its stable state having delivered a pulse1;, the duration of which is representative of the binary value of theinformation to be conveyed. The diiferentiator D derives from thetrailing edge of this pulse a short negative pulse which triggers themultivibrator 10 into its semistable state; this, inturn, will maintainthe multivibrator 3 in its semistable state for a 3'! time interval tocome. On the other hand the trailing edge of the pulse J triggers themultivibrator M into its semistable state.

The process goes further in this way until the multivibrator M returnsto its stable state, having delivered a pulse J of the suitable duration3T/2 or T (the latter being the case assumed in FIG. 3), with the sameeffects as previously as concerns the multivibrators 10 and 3.

At the time i separated by a time interval T/2 from the time at whichthe trailing end of the pulse J occurred, the conditions prevailing areexactly the same as was assumed at time 2:0.

The output signal of the multivibrator 10 is the coded message which istransmitted in any conventional way after amplification in amplifier 11.

It will readily be seen that it comprises the synchronizing pulse Ihaving a duration 3T followed by m information pulses 1 to Irespectively corresponding to pulses I; to J,,,, each of the (m-l-l)pulses being followed by a zero level of duration T/Z and each pulse I(i=1, 2 m) having a duration of either T or T/Z according to whether thecorresponding pulse J had a duration 3T/ 2 or T.

In the case of the figures, it has been assumed that all theinformations having the value 1 concerned urgent cases; therefore thepulse I has a duration T, and the pulse 1 a duration T /2.

FIG. 3 shows a corresponding decoder receiving at its input E, startingfrom a time t which will now be considered as the time origin, theaforesaid message.

The input E is connected to a duration threshold detector 13 deliveringa signal only when it receives a pulse of duration greater than 2T, Le.a synchronizing pulse l the signal delivered by the detector 13 being inthe form of a short pulse coinciding with the trailing edge of the pulseI This detector may comprise for example, in series, an integrator, abase clipper and a monostable multivibrator, the time constant of whichis very small, and which is triggered into its semistable state by thetrailing edge of the clipped signal.

The decoder comprises a chain of m bistable multivibrators Q, to Q,,,,each of which has two inputs, respectively designated 1 and 0, and twooutputs respectively designated 1 and 0. They are caused to pass intotheir states 1 and 0, respectively, when they receive, respectively attheir inputs 1 and 0, signals of increasing amplitude, i.e. the frontedges of positive signals.

Each bistable multivibrator delivers at its output 1 a signal ofamplitude 1 when it is in its 1" state, and a zero signal when it is inits 0 state, and the inverted signal at its output 0.

The input 1 of the multivibrator Q, is connected to the output of theduration threshold detector 13, and the m multivibrators are seriallyconnected, the output of each multivibrator being connected to the input1 of the following one.

The input E is also connected to a pulse generator 20 comprising adifierentiator and a monostable multivibrator, the duration of thesemistable state of which is 3T/4, and which is triggered by the frontedges of the received pulses. The positive pulses of duration 3T/4delivered by the multivibrator of the generator 20 are supplied at theoutput 30 thereof, and the corresponding inverted signal is applied tothe difi'erentiator which thus delivers a short positive pulsecoinciding with the trailing edge of the multivibrator output pulse,this short pulse being delivered at the output 31 of the generator.

With the m bistable multivibrators, m identical circuits arerespectively associated. The circuit corresponding to any one Q, (i=1, 2m) of the multivibrators will now be described.

This circuit comprises a NAND-gate (operating as an AN D'-gate followedby an inverter) P two AND-gates F and G and a further bistablemultivibrator H having output Z, which is one of the m outputs of thedecoder.

The NAND-gate P has its first input connected to the output 1 of themultivibrator Q its second input connected to the input E of thedecoder, and its output connected to the input 0 of the multivibrator QThe AND-gate F, has its first input connetced to the output of theNAND-gate P, through a differentiating circuit K and its second inputconnected to the output 30 of the generator 20. The AND-gate G has itsfirst input connected to the output 31 of this generator, and its secondinput connected to the output 1 of the multivibrator Q The multivibrator1-1,, which also has an input 0 and an input 1 (as defined hereinabove),has the former connected to the'output of the gate F and the latterconnected to the output of the gate 6;.

The bistable multivibrators H, are triggered into their states 1 and.()by the front edges of positive pulses.

The operation of the system will be described with reference to thelower portion of FIG. 3 showing the signals appearing at the input E ofthe decoder and those delivered by the elements 13, P P .P the outputs30 and 31 of the generator 20, and by the elements Q Q Q for the latterthe signals are those delivered at their output 1.

Immediately before the arrival of a synchronizing pulse I (at time 0)each multivibrator H is in the state in which it was left by thepreceding message while all the multivibrators Q; are in their state 0.Consequently the NAND-gates P deliver voltages 1. At the end of thesynchronizing pulse I the detector 13 delivers a short positive pulsewhich triggers the multivibrator Q into its state 1. For the duration ofthe pulse I the output signal from the NAND-gate P has the value 0; thisvalue becomes thereafter 1 again, which returns the multivibrator Q tothe state 0.

It will be seen that the multivibrator Q, has thus delivered at itsoutput 1 a pulse identical with pulse 1 (delivered by the multivibratorM in the coder), while the trough of the signal delivered by the NANDgate P coincides in time with the positive pulse 1 When returning tostate 0, the multivibrator Q (through its output 0) triggers themultivibrator Q into its state 1, thus playing the part assumed by thedetector 13 for the multivibrator Q Otherwise the process is exactly thesame, the multivibrator Q delivers a pulse J corresponding to that whichwas delivered by the multivibrator M in the coder and the NAN-D-gate P asignal having a trough corresponding to the pulse 1 and so on.

The multivibrators H, are respectively used for displaying thesuccessive items of the last received message on their respectiveoutputs ZS. The AN D-circuits F, are used for respectively triggeringthem into their state 0, when the information to be displayed is 0, andthe 6 AND-circuits G, for respectively triggering them into their state1, when the information to be displayed is 1.

The operation is the same for all the information items.

The value to be displayed by the multivibrator H; is 1 or 0 according towhether the duration of the pulse J; is 3T/2 or T, i.e. according towhether the duration of the the pulse I, is T or T/2. The AND-gate Frespectively receives, at its two inputs, from the generator 20 a pulseof duration 3T/4, the front edge of which coincides in time with that ofthe pulse 1 and from the diiferentiator circuit K; a short positivepulse coinciding in time with the trailing edge of the pulse Ij.

Therefore the multivibrator H; is triggered into its state "0 (if notalready therein) or not, according to whether the duration of the pulseIj is T/2 or T.

The AND-gate 6 receives at its second input the pulse 1 and at its firstinput a short pulse occurring later than the front edge of the pulse 1,.Therefore the multivibrator H is triggered into its state 1 (if notalready therein) or not according to whether the duration of the pulseJ; is 3T/2=6T/4 or T+5T/4.

What is claimed is:

1. A data coder, having an output, for the coding of messages comprisinga synchronizing signal and a number m of successive binary informationpulse signals, each of which has a duration T or T according to thevalue 0 or 1 of the corresponding binary information, said coderincluding, for the generation of said m binary signals, a circuitcomprising: m monostable multivibrators connected in series andrespectively associated with said m binary signals, said multivibratorshaving respective inputs and outputs; means for adjusting the timeconstant of each one of said m multivibrators to one or the other of thevalues T +T or T +T where T is a fixed duration, according to whetherthe corresponding binary signal is to have the duration T or Ttriggering means for triggering the first one of said m multivibratorsinto its semistable state, and a circuit coupled to said mmultivibrators fo deriving from the pulse signals generated by said Inmultivibrators corresponding shortened pulses, the duration of which isdecreased by said duration T and directing said shortened pulses,separated by intervals of duration T toward said output.

2. A coder as claimed in claim 1, wherein said circuit comprises amonostable multivibrator, the time constant of which is equal to T saidmultivibrator being referred to as the output multivibrator and havingan input coupled 0n the one hand to the outputs of said Inmultivibrators for receiving triggering signal when said Inmultivibrators pass into their stable state, and on the other hand tosaid triggering means for being triggered substantially at the same timeas said first one of said m multivibrators.

3. A coder as claimed in claim 2, wherein the duration T of saidsynchronizing signal is larger than either said duration T -i-T and T +Tand wherein said triggering means is a further monostable multivibratorhaving a time constant equal to T said further multivibrator be ingcoupled in a closed loop with said output multivibrator so that whensaid further multivibrator passes into its stable state, said furthermultivibrator is immediately caused to return to its semistable state,thereby delivering a short pulse which is applied to said first one ofsaid m multivibrators, whereby said output multivibrator automaticallydelivers successive messages, the synchronizing signal from a messagebeing separated by said time interval T, from the first binaryinformation signal of this message and from the last binary informationsignal of the preceding message.

4. A data decoder adapted for decoding the messages coded by means of acoder as claimed in claim 1, said 7 decoder comprising: an input forreceiving said coded data; first means coupled to said input fordetecting said synchronizing signal; In bistable multivibratorsrespectively associated with said In binary signals and connected inseries so that each one of the first (ml) bistable multivibrators whenpassing from its second state into its first state causes the followingone to be triggered into its second state; coupling means between saidfirst means and the first one of said m bistable multivibrators fortriggering said first bistable multivibrator into its second state;further means controlled by the trailing edges of the respectivereceived binary information pulse signals for respectively triggeringback the associated multivibrators into their first states; and inoutput circuits, respectively coupled to said m bistable multivibrators,for delivering one or the other of two predetermined signals accordingto Whether the duration of the pulse signal delivered by the associaedmultivibrator is To-i-Tg or T -i-T 5. A decoder as claimed in claim 4,wherein said first means are a duration threshold detector fordelivering a pulse coinciding with the trailing edge of saidsynchronzing signal.

References Cited UNITED STATES PATENTS 3,292,147 12/1966 Dascotte 340167RX HAROLD I. PITTS, Primary Examiner US. Cl. X.R. 340164 R

